In this April 4 photo, residents of Dala stand in line with containers to collect drinking water from a pond in suburbs of Yangon, Myanmar. Every afternoon, the long lines start to form, hundreds of men, women and children waiting to dip their plastic buckets into the lotus-filled pond, their only source of clean drinking water during the dry season of April and May.

Improving global access and sustainability of clean drinking water is part of the United Nations' Millennial Development Goals (MDGs) — a blueprint of addressing the world's most pressing needs with a target date of 2015.

Since 1990, 2.3 billion people have gained access to drinking water from improved sources. But despite this progress, 748 million people — 90% of whom live in sub-Saharan Africa and Asia — still use unimproved drinking water sources, according to an updated report the World Health Organization and UNICEF released on Thursday.

The following chart, created by Statista, breaks down the world population according to types of access to clean water. "Improved" water sources adequately prevent outside contamination, and examples include pipes, public taps and protected springs.

You can read the full report and look at additional key findings on the World Health Organization's website.